Environmental conditions in window frames with double-glazing units

The use of double-glazing units has increased steadily over the years and now sealed units are installed in most new buildings and used in replacement of windows. However, failure of double-glazing units due to condensation between the panes has occurred on many construction projects and this has demonstrated the need to use good quality units that are glazed into appropriate frames using the correct methods. A long-term exposure experiment began in 1994 to monitor the conditions around double-glazing units in various types of window frames. This experiment uses instrumentation to measure the relative humidity, temperature and the presence of liquid moisture in the cavities around the edge seal of double-glazing units. Results are reported for a 2-year monitoring period (from October 1994 to September 1996), these demonstrate differences between winter and summer periods and the effect of the external and internal environment on conditions in the glazing cavity. The implications for the durability of the double-glazing units are discussed, although, the results presented here are interim. (C) 1998 Elsevier Science Ltd. All rights reserved.